Also my apartment has more matter hidden in closets than visible matter. But I do not claim that my apartment contains any dark matter. Astronomers claim that they do not see all that there is. That is not crazy. But to build machines on Earth to search for what astronomers do not see in the sky definitely is.
Have you heard of projects to build better telescopes to clarify whether we REALLY are missing something? Or about telescopes to look more PRECISELY? Instead, the particle physics world is full of speculations claiming that dark matter is made of yet undiscovered particles.
Ok, rotation curves of galaxies are not understood. I also do not understand my husband sometimes. Neither situation is a reason to deduce that supersymmetric particles exist or to search for them.
Ok, the cosmic background radiation measurements suggest that there is much more matter in the universe than matter that is visible. But why must the unseen matter be different from the matter we see and know? I read the arguments. None is compelling. Not one.
The idea that dark matter is different from ordinary matter is a fantasy invented to get funding. And the invention really worked well: researchers got billions to check the so-called "mystery". I wish I would get funds every time my husbands lost his car keys. I would be rich by now.